1. Field of the Invention
This invention relates to an automatic temperature setback system for controlling a heating unit. Accordingly, the general objects of this invention are to provide new and improved devices and methods of such character.
2. Description of the Prior Art
In accordance with a preliminary novelty search performed on behalf of the applicant, the following U.S. patents were deemed to be of possible interest: U.S. Pat. No. Patentee Issue Date ______________________________________ 2,632,086 Hagen March 17, 1953 2,642,228 Machlet June 16, 1953 2,842,345 Brown July 8, 1958 2,984,729 Hykes et al May 16, 1961 3,231,719 DeViney et al Jan. 25, 1966 3,240,916 Bray et al March 15, 1966 3,243,609 Kompelien March 29, 1966 3,283,179 Carlisle et al Nov. 1, 1966 3,305,766 Gambill Feb. 21, 1967 3,326,275 Ray June 20, 1967 3,334,244 Hanchett Aug. 1, 1967 3,335,263 Jewell et al Aug. 8, 1967 3,341,769 Grant Sept. 12, 1967 3,356,784 Bertioli et al March 5, 1967 3,371,191 Seney Feb. 27, 1968 3,401,880 Verden Sept. 17, 1968 3,419,214 Evalds Dec. 31, 1968 3,421,691 Forbes Jan. 14, 1969 3,544,766 Muskovac Dec. 1, 1970 3,584,988 Hirsbrunner et al June 15, 1971 3,588,448 Ziver June 28, 1971 3,600,118 Hirsbrunner Aug. 17, 1971 3,670,960 Chambers June 20, 1972 3,749,884 Detmann et al July 31, 1973 3,767,936 Sweger Oct. 23, 1973 3,834,618 Buckwalter Sept. 10, 1974 ______________________________________
The foregoing patents are cited to aid the Patent and Trademark Office in the examination of this invention, such art being that known to the applicant, and for the following reasons:
Hagen, U.S. Pat. No. 2,632,086, discloses an oscillator used in the control of a heating element, such as an electric blanket.
Machlet, U.S. Pat. No. 2,642,228, discloses an apparatus which can respond to heat and uses an oscillator and carrier wave control. The circuit diagram of FIG. 4 of Machlet includes an oscillator-thermostatic element which, via a transformer, is puggable into a conventional power line of a home. A remote unit located near the burner, as also pluggable into the power line, acts as a carrier wave amplifier and detector for closing relay contacts for providing electrical power to the burner when the oscillator-thermostatic element combination is operative. Machlet terms such apparatus as a "wired radio" control of an oil burner.
Brown, U.S. Pat. No. 2,842,345, utilizes gas discharge tubes in a controller to control the heating of a resistor.
Hykes et al., U.S. Pat. No. 2,984,729, discloses a multivibrator used in a heating control for an oven.
DeViney et al., U.S. Pat. No. 3,231,719, discloses a multivibrator and a controlled rectifier firing to control a heating resistor.
Bray et al., U.S. Pat. No. 3,240,916, and Sweger, U.S. Pat. No. 3,767,936, show anticipator circuits with a silicon controlled rectifier (SCR) controlling the heating of a load.
Gambill, U.S. Pat. No. 3,305,766, is included as of interest for the plurality of SCRs, shown in his FIG. 6, utilized in a full wave voltage control system for heating loads.
Jewell et al., U.S. Pat. No. 3,335,263, discloses temperature control equipment with an astable multivibrator circuit which is used for controlling the temperature of a furnace.
Grant, U.S. Pat. No. 3,341,769, discloses circuitry for use in temperature sensitive systems including an oscillator with pulsing to an SCR and modulating alternating current. By making one or more of the resistances of a Wheatstone bridge, shown in Grant, temperature sensitive, as for example in thermometric systems, the power delivered may be made proportional to the temperature in the ambient environment to which the temperature sensitive resistor is exposed.
Bertioli et al., U.S. Pat. No. 3,356,784, discloses temperature control circuitry with circuitry including multivibrators to controlled rectifiers.
Seney, U.S. Pat. No. 3,371,191, discloses heater control through modulation and amplification to a thyratron tube.
Verden, U.S. Pat. No. 3,401,880, and Forbes, U.S. Pat. No. 3,421,691, disclose a SCR which fires with current to a heat accumulator which affects a thermostat.
Evalds, U.S. Pat. No. 3,419,214, shown SCR and bridge circuitry in temperature regulating apparatus.
Muskovac, U.S. Pat. No. 3,544,766, discloses a firing circuit for proportionally controlling energy to a load from an alternating source. The circuit includes a thyristor in series connection with the load and source, a gate circuit, and connection to the gate of the thyristor and the source for generating an application of trigger pulses to the gate. The gate circuit has a sensor branch which includes a conditioning responsive impedance. The sensor branch controls the application of the trigger pulses with respect to the conductive half cycles of the source in response to the condition and initiates thyristor conductions in response thereto. The sensor branch is cycled to provide timed proportional control of the thyristor. In one embodiment of Muskavac, cycling means is included within the sensor branch and impresses a cyclic voltage variation on the impedance. In another of his embodiments, an auxiliary load produces the condition aspired with the main load and is closely coupled to the condition responsive impedance so as to cause a secondary firing cycle imposed upon a primary cycle resulting from the impedance response to average environmental conditions.
Chambers, U.S. Pat. No. 3,670,960, is of interest for its showing of pulsing and use of SCRs in heating control.
Buckwalter, U.S. Pat. No. 3,834,618, discloses a separate unit thermostat the regular heater control with a timer which allows heat from a heat source to affect a thermostat under which it is placed to obtain a temperature setback level for a predetermined time.
The remaining cited patents, set forth above, all show some circuit similarities to applicant's disclosure and, therefore, are included as of interest. However, such patents are considered not to be anticipatory, in the slightest, whether considered by themselves or in any combination thereof.
The most pertinent of the foregoing cited patents, with respect to the instant invention, is the patent to Buckwalter, U.S. Pat. No. 3,834,618. Applicant's device operates differently and has a different principle than Buckwalter, though one of the goals of both Buckwalter and the applicant are common, namely to conserve energy during the nighttime. The comments made by Buckwalter in certain portions of his specification are pertinent to applicant's invention, and hence several paragraphs following hereinbelow which were applicable to Buckwalter are also applicable to this instant invention:
Both inventions, in part, relate to apparatus for automatically setting back the temperature of a room controlled by a conventional heating system during selectable time periods.
As background of the invention, Buckwalter stated, and it is equally applicable here, that:
"Conventionally one may manually set a thermostat back to a lower night time temperature for comfort or fuel economy. This manual setback method has a disadvantge in that the temperature in the morning is too cold for comfort. Devices for automatically varying the temperature of a room during night time hours have been widely employed and described in the art and provide the comfort of a warm-up before arising. Typically, a timer is employed to determine when a temperature setback condition is to become effective. An early U.S. Pat. No. describing a timer in use with a thermostat controlled heating system is the patent to Otis U.S. Pat. No. 1,207,618. A night and day time temperature regulating system is described in the U.S. Pat. Nos. 1,876,636 and 1,931,464 to Dicke. The U.S. Pat. No. 1,876,636 described a heat source which simulates a change in temperature of a room by applying heat to a thermostat. The heat source thus causes the thermostat to register a higher room temperature than actually exists and thus inhibits the heating system operative in the room from being energized as long as the heat source is on. In response to this simulation, the thermostat de-energizes the heating system operative in the room to obtain, for example, a cooler night time room temperature with a corresponding saving in fuel. The system described in the Dicke patents requires substantial wiring to install with electrical connections to the heating system to bring the clock operated temperature setback mechanism into operation. Such structural changes may be convenient to install during the building of a house but require extensive work to install with existing heating systems.
"In the German patent publication Auslegeschrift No. 1,248,261 applied for in 1964 and laid open for inspection Aug. 24, 1967, a glow lamp is employed adjacent to a temperature sensor to simulate a higher temperature when a timer enables electrical power to be applied to the glow lamp. Energization of the glow lamp provides a high temperature simulation, which causes closure of a heating fluid control valve connected in series with a radiator. The timer controlled heating system described in the German patent prevents any heat from reaching the radiator during the time the timer energizes the glow lamp. Thus the room temperature slowly descends to whichever external temperature may exist until the timer disables the glow lamp to enable resumption temperature the heating system.
"Other recent patents relating to temperature setback devices are in U.S. Pat. No. 3,386,496 to O'Connor, and to Schuller U.S. Pat. No. 3,525,222. In the Schuller patent a temperature regulator for an electric refrigerator is described wherein a heat source simulates a requirement for refrigeration in excess of what is actually necessary in order to maintain the refrigerator temperature sufficiently below the dew point. U.S. Pat. No. 3,251,549 to Hewitt, Jr. et al., relates to an illuminated thermostat for use with a domestic heat control system.
"A significant disadvantage and inconvenience of temperature setback devices described in these various patents involves the extensive structural changes needed to install a temperature setback device in existing domestic heating systems. The installation commonly requires the addition of wires which are routed inside walls and floors to connect to furnace controls. These modifications tend to increase the cost of a night time temperature setback device with an expensive charge for installation. As a result, the extensive use of temperature setback devices has been less attractive to the home owner. Yet a widespread use of night time temperature setback devices would be of significant advantage in any age where energy conservation is beneficial to the public and is a publicly recognized and supported policy."
In essence, Buckwalter, U.S. Pat. No. 3,834,618, utilizes a temperature setback control including a housing which may be utilized with existing heating systems by mounting the housing with this control within an airflow influencing distance from a conventional room thermostat which controls the heating system. The Buckwalter housing produces a convection flow of heated air during a setback time period to obtain a temperature setback level in the room heating zone or building in which the thermostat is located. A temperature sensor (actually another thermostat) regulates the operation of the control to maintain the room at the setback temperature level determined by the value set on the separate thermostat. A housing to enable the influencing of the thermostat with the convection flow of heated air is described by Buckwalter.